De or het ontremming?

The correct Dutch article is:

de ontremming

Rule Words ending in -ing: almost always de. See the rule

How to use ontremming

the ontremmingde ontremming
this ontremmingdeze ontremming
that ontremmingdie ontremming
our ontremmingonze ontremming
your ontremmingjouw ontremming
every ontremmingelke ontremming
which ontremming?welke ontremming?
a big ontremming / the big ontremmingeen grote ontremming, de grote ontremming